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So, the Objective2 headphone amp - designed entirely around the measurements? (PLEASE READ RULES BEFORE POSTING)

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  1. Steve Eddy


    Quote:

    Yes, Sprtizer went to town on Rudistor. Not some "design" that materialized out of nowhere.
     
    Quote:
     
    I don't see any posts by NwAvGuy. Are you suggesting he's posting using a sockpuppet account?
     
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    Well, there's a first time for everything.
     
    Personally I think going beyond banning someone and taking it to the point that the person cannot be mentioned and even prohibiting links to threads on other forums where the banned individual posts is rather over the top. It's right out of Orwell's 1984 and the old Soviet Union (see "unperson" or "nonperson"). And I only suggested this thread be removed when I discovered it had been taken to such an absurd extreme.
     
    se
     
     
    maverickronin likes this.
  2. c61746961
    ... or out of kindergarten. Maybe this thread should go, but not until there's another one with actual measurements and impressions over the finished product. This amp deserves the spotlight because it bears a flag, let the community decide if it's worthy.
     
    Maxvla likes this.
  3. Satya
    Quote:
     
    Just to check: if a banned, petulant person who happens to be a headphone amp designer has an amp design that you, as a member of the trade, are planning to sell, and there was much anticipation and posting occurring that is potentially leading to a flurry of said amps being bought and sold, would that thread be OK? 
     
    For the earlier post that stated "(a)llowing a thread for the discussion and critiquing of a particular individual's design without that individual being able to respond to any of it is eminently unfair":  - do you mean to say that are you sticking up for the disadvantaged designer?  Just to check: say the amp was designed by a Chinese electronics wizard that does not speak English and therefore cannot participate effectively in this forum, but based on preliminary indications has a great amp that you, as a member of the trade, intend to sell - would you feel more comfortable with a thread in which the designer cannot participate and respond to critiques?
     
    I may end up buying a pre-made version of this amp because of how it performs, regardless of whether the designer is petulant or a saint.   I believe it is possible to separate the design from the designer.
     
  4. Anaxilus


    Quote:

    Well if that is the crux of your point I can't say I disagree.  We are however moving beyond the scope of the thread though to a completely separate issue but your argument is not without merit.
     
     
  5. fishski13

     
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    i build as a hobby - maybe 8 amps a year.  i have zero interest in being profit driven.  i am actually building the amp for free, parts cost only. 
     
     
     
  6. Shike


    Quote:

    How is it bad for the DIY community?  If the measurements are to be believed it's one of the best performing in-spite of cost amps out there.  Please explain how that's a bad thing.
     
  7. upstateguy


    Quote:


    sockpuppet300.jpg
     
  8. Steve Eddy


    Quote:

    No, I'm not sticking up for a particular individual. I'm sticking up for the underlying principle of the matter.
     
    Quote:
     
    First, I don't know why you bring in this "intend to sell" bit. Speaking for myself, I've no intention of selling anything having to do with the O2.
     
    Second, I make a distinction between whether or not a particular person is able themself to participate and their specifically being prohibited from participating.
     
    Quote:
     
    Certainly it's possible to separate the design from the designer when it comes to a simple purchasing decision.
     
    But until designs start spontaneously materializing out of thin air, I don't see how it's possible to separate the design from the designer when it comes to discussing and critiquing the design itself.
     
    se
     
     
     
  9. Satellite_6
    I have to say I agree with se. . . 
     
    At the very least the rules do need to be changed because they are misleading/inaccurate. 
     
  10. amb


    Quote:
     
    So you're arguing that the amp is only designed for portable usage with weak sources, yet force the use of AC power (which in this design, gives about 7Vp-p more swing from one rail to another than on battery power)?
    [​IMG]
     
    You also forgot to account for one more 0.5V drop because there are two 1N5818 schottky diodes -- one on each rail.
     
    Quote:
     
    No it's worse than that.  You fail to account for the fact that the opamp is not rail-to-rail so it will clip several volts before the signal peaks swing to the rails.  That will cut about 4Vp-p off the available swing.  And subtract the missing 0.5V schottky drop, you're now left with 19Vp-p swing before clipping, and with a gain of 2x, the input cannot be more than 9.5Vp-p which is 3.4Vrms.  If you give the amp a 4Vrms signal, it will clip even on AC power.  Set the gain any higher than 2x and it will clip worse.
     
    Quote:
     
    I already demonstrated above that the amp cannot handle 4Vrms input on AC power, let alone battery power which gives 7Vp-p less swing.  With 2Vrms input and gain of 2x, indeed you have 6.2Vrms, which is 17.5Vp-p.  This is only 1.5V before the 19Vp-p maximum swing, which is only 0.7dB headroom.
     
    With battery power, in my original post I showed that the amp could only swing 11.8Vp-p, so the 2Vrms input and 3.1x gain will clip severely.
     
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    The "NJM2608" in my original post was a typo.  I really meant NJM2068, which is the opamp the designer chose for the input.
     
     
  11. Satya
    Quote:

    Thanks for the reply.  Where I am coming from is that, as someone who 'showcases' the AMB designs (per your 4/29 post regarding the M3), designs which were recently criticized by the designer of the O2, I have to keep that in mind as I read your posts.
     
     
     
     
  12. Shike
    I've asked nwavguy about the 4V - he states this is regarding DAMAGING the amplifier and not in regards to clipping.  Using the default gain 2.25V should be safe for low distortion, or a lower gain can be used.
     
  13. Satya
    Fair enough.  As this amp gets built and tested by DIYers, the designer will presumably be criticized or lauded for a variety of reasons, one of which will hopefully be how the amp sounds.
     
    Quote:


     
     
  14. amb
     
    Quote:

    I assume "default gain" is 2x.  A 2.25Vrms input will give 4.5Vrms output, which is 12.7Vp-p.  This is almost a volt beyond the 11.8Vp-p maximum swing of the amp running on batteries and therefore will clip.
     
     
  15. Shike


    Quote:
     
    "When the O2 is running from battery it's much more likely a battery powered source is being used and none of those produce anything close to 2 V RMS of output.

    On AC power the O2 produces acceptably low distortion even with 2.25V RMS input at the default gain settings. If you don't like those gain settings, they can easily be lowered. I haven't even determined what the best default gain settings are yet (and have posed that question on diyAudio). At 2X or 2.5X gain there's zero chance the O2 will have any issues at all."
     
    From the horses mouth.  I'm sure you can find one of the many threads to discuss this directly with him if you're interested or shoot him an email.
     
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